1. Field of the Invention
The present invention relates to a method of manufacturing a light emitting diode package and, more particularly, to a method of manufacturing a light emitting diode package which forms a micro structure for improving light extraction efficiency of a light emitting diode.
2. Description of the Related Art
A light emitting diode is a semiconductor device for converting electric energy to light energy and is composed of a compound semiconductor that generates a particular wavelength of light according to an energy band gap. Recently, light emitting diodes are utilized in various applications such as optical communication, display and the like.
Light emitting diodes are provided in packages designed in accordance with the purpose and required configuration. In general, to manufacture a light emitting diode package, a light emitting diode chip is mounted on a substrate or a lead frame with an electrode pattern formed thereon, a terminal of the chip is electrically connected to the electrode pattern (or the lead) and a resin encapsulant is formed over the chip using an epoxy, silicone or combinations thereof.
FIG. 1 illustrates an example of a conventional light emitting diode package.
Referring to FIG. 1, the light emitting diode package 10 includes a lower package substrate 11a with two electrode patterns 12a and 12b formed thereon and an upper package substrate 11b with a recess formed therein. A light emitting diode chip 15 is mounted on a bottom of the recess using an adhesive layer 14. The two electrodes (not shown) of the light emitting diode chip 15 can be connected to upper ends of the lead frames 12a and 12b by wires.
The light emitting diode chip 15 is surrounded by a resin encapsulant 16. The resin encapsulant is an important component that affects the light emission efficiency of the light emitting diode package 10. That is, the light emitted from the light emitting diode chip 15 can vary in the amount extracted to the outside depending on the optical characteristics (especially, the refractive index) and the shape of the resin encapsulant 16.
In particular, a transparent resin such as an epoxy resin or a silicone resin of the resin encapsulant 16 has a refractive index (e.g. epoxy resin: 1.5) higher than that of the external atmosphere, and thus the light amount extracted in actuality is limited by the light extraction critical angle determined thereby. Therefore, a considerable portion of light deviating from the critical angle range in the resin encapsulant 16 is internally totally reflected and not extracted to the outside or comes to have complex light paths. This results in low light extraction efficiency.
In addition, as shown in FIG. 1, when a liquid transparent resin is injected through a dispensing procedure, etc. to form the resin encapsulant 16 in the recess such as in the case of a side-view light emitting diode package, the encapsulant forms a curved surface due to the wettability of the liquid resin, which results in low light extraction efficiency.